The present invention relates to a production planning system, or more in particular to a production planning system including the elimination of deficient parts, elimination of superfluous parts, adjustment of a production plan and adjustment of a parts acquisition plan.
Well-known techniques for a production planning system include
(1) the technique described in JP-A-5-108661 PA1 (2) the technique described in JP-A-5-342220 PA1 a data storage unit for storing production plan information, parts list information, parts in-stock information and parts warehousing schedule information; PA1 a MRP (material resource planning) explosion unit for calculating the required amount of material resources based on the production plan information and the parts list information stored in the data storage unit; and PA1 a superfluous parts adjusting unit for making adjustment to eliminate superfluous parts; PA1 wherein the superfluous parts adjusting unit includes a superfluous parts calculation section for calculating superfluous parts by collating the required amount of material resources calculated by the MRP explosion unit with the parts in-stock information and the parts warehousing schedule information, and a superfluous parts elimination section for eliminating superfluous parts by changing the production plan based on the superfluous parts information calculated by the superfluous parts calculation section. PA1 a unit for storing production plan information, parts list information, parts in-stock information and parts warehousing schedule information for all products to be produced; PA1 a unit for forming a feasible production plan by calculating the required amount of material resources for the current production plan stored in the storage means, collating the result of explosion of the required amount of material resources with the parts in-stock and the parts scheduled to be warehoused stored in the storage means thereby to calculate the type of the parts and the number of the parts deficient for carrying out the current production plan, determining that the current production plan is infeasible for any of the products to be produced in the case where the number of deficient parts for the particular product is not zero, and selectively deleting the portion of the production plan for a product using the deficient parts from the infeasible plan for the particular product, and thereby resolving the infeasibility of the production plan due to the deficient parts; and PA1 a unit for forming a new production plan by calculating the required amount of material resources for the production according to a feasible production plan, collating the parts in stock and the parts scheduled to be warehoused stored in a storage unit, calculating the type of superfluous parts and the number of the superfluous parts for executing the current production plan, determining whether or not a new production plan can be formed for a product using only the superfluous parts in the case where the number of the superfluous parts is not zero for any of the products to be produced, and adding a new production plan to the feasible production plan in the case where the new production plan can be formed thereby to reduce the superfluous parts. PA1 a unit for storing production plan information, parts list information, parts in-stock information and parts warehousing schedule information for all products to be produced; PA1 a unit for calculating the required amount of material resources for the current production plan stored in the storage unit; PA1 a unit for calculating the type of parts and the number of the parts deficient for executing the current production plan by collating the result of explosion of the required amount of material resources with the parts in stock and the parts scheduled to be warehoused stored in the storage unit; PA1 a unit for forming a feasible production plan by determining the current production plan as infeasible for any of the products to be produced for which the number of deficient parts is not zero, and selectively cancelling the portion of the production plan for the product using the deficient parts from the feasible production plan for the particular product thereby to resolving the infeasibility due to the deficient parts; PA1 a unit for calculating the required amount of material resources for the feasible production plan; PA1 a unit for calculating the parts and the number of the parts superfluous for executing the current production plan by collating the required amount of material resources with the parts in stock and the parts scheduled to be warehoused stored in the storage unit; and PA1 a unit for determining whether or not a new production plan can be formed for a product using superfluous parts alone in the case where the number of the superfluous parts is not zero, and adding the new production plan to the feasible production plan in the case where the new production plan can be formed thereby to reduce the superfluous parts; PA1 said units being realized by a computer. PA1 calculating the required amount of material resources for the current production plan, collating the calculation result of the required amount of material resources with the parts in stock and the parts scheduled to be warehoused thereby to calculate the type of parts and the number of the parts deficient for carrying out the current production plan, determining the current production plan as infeasible in the case where the number of the deficient parts is not zero, and eliminating the deficient parts by selectively deleting the portion of the production plan for the products using the deficient parts from the infeasible production plan thereby to form a feasible production plan; and PA1 calculating the required amount of material resources for the feasible production plan, collating the result of calculation of the required amount of material resources with the parts in stock and the parts scheduled to be warehoused thereby to calculate the parts and the number of parts superfluous for carrying out the feasible production plan, determining whether or not a new production plan can be formed for a product using superfluous parts alone in the case where the number of the superfluous parts is not zero, and reducing the superfluous parts by adding a new production plan to the feasible production plan in the case where the new production plan can be formed, thereby converting the feasible production plan into a production plan with the superfluous parts reduced.
The conventional technique disclosed in JP-A-5-108661 is a production scheduling system in which a production schedule solution of minimum cost is predetermined as an optimum solution according to mathematical programming, and the rationality of the artificial operation is sought after by indicating the effect that the artificial correction of the schedule has on the minimum cost.
The conventional technique (2) disclosed in JP-A-5-342220, on the other hand, is a process planning evaluation system in which a process planning is quantitatively evaluated by converting the amount of a product in stock and the rate of a product out of stock into a cost and simulating the change of the particular cost.
The production scheduling system according to the conventional technique (1) described above seeks after the rationality of the artificial operation by executing the following steps. Specifically, a time schedule is determined for actually carrying out the production based on the line, quantity and the delivery time of a product to be manufactured under such restraints as the product quantity, delivery time, the lead time for acquisition of raw materials and the maximum available workforce. In determining this time schedule, the actual restraints are approximated or simplified to predetermine a production schedule solution of minimum cost as an optimum solution according to the mathematical programming. After that, the production schedule is artificially corrected in such a manner as to satisfy the actual restraints based on the approximated or simplified restraints, or to give priority to a specific product unconditionally for the reason of sales without regard to the cost. These artificial corrections are monitored and evaluated, and if not realizable, an alarm is issued against them, while if realizable, the effect on the minimum cost obtained as the optimum solution of mathematical programming is calculated and the result is displayed. The conventional technique (1) described above is a method for calculating and displaying the effect that an artificial operation of a production scheduling causing superfluous parts has on the minimum cost obtained as an optimum solution of the mathematical programming, but has no function of providing a procedure for eliminating actual superfluous parts.
The conventional technique (2) described above, on the other hand, is a process planning evaluation system in which process planning data and incoming order prediction data are prepared from the achievements of the previous year, the amounts of a product in stock and a product out of stock are determined by simulating such data. The process planning is quantitatively evaluated by converting the amount of the product in stock and the product out of stock into a cost according to a predetermined formula. Then, the operator checks the figures, and if necessary, corrects the process planning. In the conventional technique (2), therefore, a superfluous product in stock is determined by simulation and converted into a cost and displayed sometimes to request the correction of the process planning, but no procedure is provided for eliminating actual superfluous parts.
In correcting a production plan upward according to the conventional method, parts newly required, if any, are not purchased, but superfluous parts in stock are checked for and if there are any, they are delivered out to reduce the stock. The conventional method, however, is not intended to positively search the superfluous parts for automatically determining a product that can be manufactured, select a proper one out of a plurality of products that can be manufactured and add it to the production plan.
Also, even when superfluous parts are eliminated by the upward correction of the production planning, a subsequent change in the production plan for eliminating deficient parts may generate superfluous parts anew. In the case where a new production plan is added by combining superfluous parts and newly acquired parts, for example, a subsequent change of the line from a product using deficient parts to a product using no deficient parts for eliminating the deficient parts converts the otherwise superfluous parts into required parts, with the result that the newly acquired parts become superfluous parts.